what are common 8.25 problems

1300ZUK · **Posted:** Thu Mar 29, 2007 10:21 am

?
just curious, rear end is making a noise?

ATXKJ · **Posted:** Thu Mar 29, 2007 11:17 am

Check the oil level.

I don't think the 8.25 has any history of problems - I think it's pretty reliable - the couple of posts with problems have been due to aftermarket locker installs.

However any diff can leak or have contaimination problems - a noise could be a bearing - or if you've just had work - then the pinion/ring gear spacing - but once that's set it doesn't move much.

Are you sure it's the Diff? - tire noise can be an issue (change pressure for a short time to see) and u-joints can make noise - although it tends to be clunking as you start off/ stop.

1300ZUK · **Posted:** Thu Mar 29, 2007 11:21 am

ATXKJ wrote:

Check the oil level.

I don't think the 8.25 has any history of problems - I think it's pretty reliable - the couple of posts with problems have been due to aftermarket locker installs.

However any diff can leak or have contaimination problems - a noise could be a bearing - or if you've just had work - then the pinion/ring gear spacing - but once that's set it doesn't move much.

Are you sure it's the Diff? - tire noise can be an issue (change pressure for a short time to see) and u-joints can make noise - although it tends to be clunking as you start off/ stop.

took in for unrelated tranny problem, now they are sure i have a rear end problem, which i can probably agree with, it was getting noisey but i couldn't tell if it was the road or the tires and hadn't invistgated anymore because it has 50K miles on it, not really expecting driveline troubles. So i guess if i had to take a stab at it, the preload is messed up. Just trying to see what it could be

sleeve84028 · **Posted:** Thu Mar 29, 2007 1:02 pm

Have you changed out the fluid recently? First and foremost step is to check the pumpkin for the proper amount of fluid and determine what it looks like. Every rearend should be almost completly quiet for its entire service life. Sure a seal can fail once in a while but for the most part the rear end is a very solid piece

Can you describe the noise? Does it happen on accel, decel, turning or when you are just cruising along through all of the potholes?

ARBSeth · **Posted:** Thu Mar 29, 2007 1:37 pm

Growling = Axle bearings gone, torn up spider gears or broken teeth on the Ring gear or pinion...
Howling is almost always bearing related or your backlash is too tight. Have you messed with that lately?
Thunking is bad times... you've lost preload on something, usually your carrier bearings. That can break teeth, too.
Take the cover off and see if you have any shavings in the oil... if you don't see any chunks of metal and just shavings, you roasted a bearing... probably on the axle... a rebuild kit will run you no more than $100 bones.

Pretty technical diagnosis, huh? But you'll find 9-10 times that it's right.

1300ZUK · **Posted:** Thu Mar 29, 2007 7:39 pm

yippie!!!!

they can't figure out the tranny issue and my carrier bearing is supposedly toast.

51K miles :roll:

should have bought a 'yota.

USPLibby · **Joined:** Thu Jul 28, 2005 12:29 am **Posts:** 377

My Pinion bearings went out at around 60K+. :cry:

Tokyojoe · **Posted:** Thu Mar 29, 2007 7:59 pm

1300ZUK wrote:

yippie!!!!

they can't figure out the tranny issue and my carrier bearing is supposedly toast.

51K miles :roll:

should have bought a 'yota.

Did you buy your KJ new or used?

1300ZUK · **Posted:** Thu Mar 29, 2007 8:16 pm

Tokyojoe wrote:

1300ZUK wrote:

yippie!!!!

they can't figure out the tranny issue and my carrier bearing is supposedly toast.

51K miles :roll:

should have bought a 'yota.

Did you buy your KJ new or used?

used? why?

Jeepjeepster · **Posted:** Thu Mar 29, 2007 10:04 pm

1300ZUK wrote:

Tokyojoe wrote:

1300ZUK wrote:

yippie!!!!

they can't figure out the tranny issue and my carrier bearing is supposedly toast.

51K miles :roll:

should have bought a 'yota.

Did you buy your KJ new or used?

used? why?

That can be the problem many times.

If you dont stay on Schedule with oil changes, the Jeep wont like you.

1300ZUK · **Posted:** Thu Mar 29, 2007 10:40 pm

Jeepjeepster wrote:

1300ZUK wrote:

Tokyojoe wrote:

1300ZUK wrote:

yippie!!!!

they can't figure out the tranny issue and my carrier bearing is supposedly toast.

51K miles :roll:

should have bought a 'yota.

Did you buy your KJ new or used?

used? why?

That can be the problem many times.

If you dont stay on Schedule with oil changes, the Jeep wont like you.

well yes, but it had 32K miles on it when i got it, wasn't beat on by previous owner (yes you can tell) so it had to be an error in the factory at 51K.

unixxx · **Posted:** Thu Mar 29, 2007 10:46 pm

Replacing the carrier bearings only takes a couple hours if you learn to set the backlash. You'll just need a couple new bearings/races, gear lube, RTV, an 8.25" preload tool, and a factory service manual. If you don't have a bearing puller you can cut the bearings off with a Dremel. Just don't get any shavings into the differential. I wouldn't really trust the dealership to properly set the backlash.

1300ZUK wrote:

yippie!!!!

they can't figure out the tranny issue and my carrier bearing is supposedly toast.

51K miles :roll:

should have bought a 'yota.

1300ZUK · **Posted:** Thu Mar 29, 2007 10:52 pm

unixxx wrote:

I wouldn't really trust the dealership to properly set the backlash.

yes this is what worry's me, take it to dealer they "fix" it, then 10K miles later some thing.

ARBSeth · **Posted:** Fri Mar 30, 2007 11:02 am

Setting backlash on an 8.25 is probably about as easy as it gets... side adjusters make it a snap. The spanner tool runs about $45 or so and you'll use it exactly once... so I'd just pony up and pay for it... and if the lash was wrong from the factory, no way it lasts 50K.... the guy probably towed too much weight with the KJ and burnt up the carrier bearings by not changing the oil. Used to make my living off guys like that when I worked for a diff shop. Just have them set it at 0.006 lash for used gears and you're kosher. Be sure to change all the bearings, though... you've got metal floating in there, and the other Pinion and axle bearings no likee metal shavings... go cheap and you're doing it again in a couple months...

sleeve84028 · **Posted:** Fri Mar 30, 2007 12:57 pm

ARBSeth wrote:

...burnt up the carrier bearings by not changing the oil....

Proper maintainence really pays off in the long run.

krazz1e · **Posted:** Fri Mar 30, 2007 2:41 pm

uhhh setting up pinion preload and gear depth on a 8.25 isn't the easiest in the world, it is easier than a dana axle cuz you don't need to shim anything but toy carrier is much easier to work on because you can put it on a bench. Unless you have experience I would not suggest this, you'll just end up setting it wrong and destroying the R&P plus the new bearings. Take it to a driveline shop instead of the dealer (six states).

unixxx · **Posted:** Fri Mar 30, 2007 3:03 pm

I actually found the C8.25 screw adjusters to be a pain. The carrier needs to be reseated everytime you make an adjustment and the tool's inconvenient. I'll see how the D30a compares when I install my RD100 this weekend.

Seth, do you have any recommendations for setting the carrier bearing preload on the shim-based D30a?

ARBSeth · **Posted:** Fri Mar 30, 2007 3:14 pm

Set up bearings... ream out your old ones so they slide on and off... it doesn't matter if they're loose for set up, you only need the width of the bearing to be correct to set up the lash. Saves a lot of time. And always reuse your old stack to start... or at least Mic them and use new ones.

Pinion bearings aren't easy to preload, but if you're just rebuilding like this poor guy, reuse your old shims and it should set up the first time because you didn't change anything. Always check your pattern on the set up, though. Changing gears is what throws the shims out... not bearings. R/G lash will loosen over time... the gears wear and move away from one another... just push the carrier back into the pinion and lighten it slightly to get it to the right lash.

pg2676 · **Posted:** Sat Mar 31, 2007 10:20 am

My rear had to be rebuilt @ 105,000km (65,000 miles). Covered on warranty. Since then I've started towing a tent trailer, so I've gone with 75W140 Amsoil this year. I think the dealer is just defaulting to 80W90 Mopar Synthetic on all diffs that come through their shop, which may have contributed to the problem.

1300ZUK · **Posted:** Mon Apr 02, 2007 12:10 am

you go with 75W140 in Alberta, even in the middle of winter :shock:

isn't it a little rough rollin' on those cold days :lol:

what are common 8.25 problems

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